Predictive value of caliceal pelvic height-to-infundibular length ratio for stone-free rate in lower calyx stone treatment with flexible ureteroscopic lithotripsy
10.3760/cma.j.cn112330-20241014-00452
- VernacularTitle:肾盂下盏高度与肾下盏漏斗部长度比值对输尿管软镜治疗肾下盏结石清除率的预测价值
- Author:
Shiwei HUANG
1
;
Sheng ZHONG
;
Guangming YIN
;
Long WANG
;
Zhiqiang JIANG
;
Kai HUANG
;
Jing TAN
Author Information
1. 中南大学湘雅三医院泌尿外科，长沙 410013
- Publication Type:Journal Article
- Keywords:
Kidney calculi;
Lower pole kidney;
Ureteroscopes;
Stone free rate;
Influencing factors
- From:
Chinese Journal of Urology
2025;46(8):600-606
- CountryChina
- Language:Chinese
-
Abstract:
Objective:This study aims to explore the predictive value of the ratio of caliceal pelvic height to infundibular length（CPH/IL）for the stone-free rate（SFR）in the treatment of lower calyx stones using flexible ureteroscopic lithotripsy（FURL）combined with a distally bendable negative pressure suction sheath.Methods:A retrospective analysis was conducted on the clinical data and anatomical parameters of 312 patients with lower calyx stones or combined lower calyx stones admitted to the Third Xiangya Hospital of Central South University from September 2022 to December 2023，all of whom were treated with FURL combined with a distally bendable negative pressure suction sheath. Stone clearance was defined as no residual stones or residual stones with a diameter of ≤3 mm without any symptoms. Patients were divided into the clearance group（265 cases，84.90%）and the non-clearance group（47 cases，15.10%）. There were no significant differences in gender（male/female：173/92 cases vs. 29/18 cases），age［（44.69 ± 13.14）years vs.（42.60 ± 10.93）years］，degree of hydronephrosis（no hydronephrosis/mild hydronephrosis/moderate to severe hydronephrosis：122/85/58 cases vs. 21/12/14 cases），side of lower calyx stones（left/right：157/108 cases vs. 31/16 cases），maximum diameter of stones（MDS）［（19.23 ± 6.41）mm vs.（17.77 ± 6.18）mm］，and CT value of stones［（993.46 ± 249.12）Hu vs.（1013.43 ± 300.90）Hu］between the two groups（ P > 0.05），indicating comparability between groups. There was no significant difference in the distance from the midpoint of the lower lip of the renal pelvis to the ureter at the lowest plane of the lower calyx（K-A line）between the clearance and non-clearance groups［（26.16 ± 5.18）mm vs.（25.70 ± 8.66）mm， P > 0.05］. However，significant differences were observed in the infundibulopelvic angle（IPA）［（53.97 ± 15.72）° vs.（37.43 ± 15.39）°］，infundibular length（IL）［（27.26 ± 5.11）mm vs.（33.04 ± 7.38）mm］，infundibular width（IW）［（8.27 ± 2.82）mm vs.（7.09 ± 3.20）mm］，caliceal pelvic height（CPH）［（19.96 ± 4.63）mm vs.（30.32 ± 7.56）mm］，ureter-lower calyx distance（ULD）［（23.00 ± 5.59）mm vs.（18.78 ± 6.31）mm］，CPH/IL ratio［（0.73 ± 0.11）vs.（0.92 ± 0.09）］，and curvature of the lower calyx of the renal pelvis［（0.06 ± 0.01）mm -1 vs.（0.08 ± 0.03）mm -1］between the two groups（ P <0.05）. Univariate and logistic multivariate regression analyses were used to identify the independent risk factors affecting the postoperative SFR of FURL-treated lower calyx stones and to assess the value of CPH/IL for SFR in the treatment of lower calyx stones using FURL combined with a distally bendable negative pressure suction sheath. A logistic multivariate regression model and a corresponding nomogram were constructed，and the predictive ability of the model for SFR was evaluated using the receiver operating characteristic（ROC）curve. The calibration curve and the Hosmer -Lemeshow test were used to assess the consistency and accuracy of the model. The clinical utility of the model was evaluated using decision curve analysis（DCA）. Results:Univariate analysis revealed that seven anatomical parameters differed significantly between the clearance and non-clearance groups（all P < 0.05）：infundibulopelvic angle（IPA， OR = 0.27，95% CI 0.17-0.42， P < 0.01），infundibular length（IL， OR = 2.52，95% CI 1.83-3.47， P < 0.01），infundibular width（IW， OR = 0.64，95% CI 0.45-0.90， P = 0.011），caliceal pelvic height（CPH， OR = 5.78，95% CI 3.67-9.10， P < 0.01），ureter-lower calyx distance（ULD， OR = 0.43，95% CI 0.30-0.63， P < 0.01），CPH/IL ratio（ OR = 13.62，95% CI 6.86-27.03， P < 0.01），and curvature of the lower calyx of the renal pelvis（ O = 3.15，95% CI 2.08-4.78， P < 0.01）. Multivariate logistic regression further identified CPH/IL（ OR = 9.87，95% CI 4.92-19.79， P < 0.01），IPA（ OR = 0.41，95% CI 0.23-0.71， P = 0.001），and ULD（ OR = 0.50，95% CI 0.29-0.87， P = 0.014）as independent risk factors influencing the stone-free rate after flexible ureteroscopic lithotripsy combined with a distally bendable negative-pressure suction sheath. The area under the ROC curve（AUC）of the univariate regression model showed that for IPA，the AUC was 0.788（95% CI 0.711-0.864）；for IL，it was 0.731（95% CI 0.643-0.819）；for ULD，it was 0.677（95% CI 0.586-0.767）；for CPH，it was 0.867（95% CI 0.804-0.929）；for IW，it was 0.628（95% CI 0.535-0.721）；for CPH/IL，it was 0.906（95% CI 0.850-0.961）with an optimal cutoff value of 0.882，corresponding to a sensitivity of 83.02% and a specificity of 92.08%；and for curvature of the lower calyx of the renal pelvis，it was 0.744（95% CI 0.662-0.827）. The AUC of the multivariate regression model was 0.929（95% CI 0.884-0.974）with an optimal cutoff value of 0.364，corresponding to a sensitivity of 82.98% and a specificity of 95.09%. Calibration curves demonstrated close agreement between the predicted and actual stone-free rates after FURL（C-index = 0.921）. The Hosmer-Lemeshow goodness-of-fit test indicated no significant discrepancy between predicted and observed probabilities（ P = 0.135，>0.05）. Decision-curve analysis further revealed that basing clinical decisions on the model ，s predicted probability yields a higher net clinical benefit than either withholding FURL for all patients or treating all patients regardless of risk，and it also outperforms strategies guided by any single independent predictor alone. Conclusions:IPA，IL，IW，CPH，ULD，CPH/IL ratio，and curvature of the lower calyx of the renal pelvis can all predict the postoperative SFR of FURL combined with a distally bendable negative pressure suction sheath for the treatment of lower calyx stones to varying degrees. Among them，CPH/IL has the highest predictive value. When CPH/IL >0.88，it may be difficult to use FURL to treat lower calyx stones.
